vaccuum problems!?!?!

[Tayohs 95Gt]

alright i hooked up a vac gauge to my car.. and when it idled down it went down to 9-10 and it was idleing at 900-1100 and it caused an iratic idle and kinda made the car want to stall.. when i woulod give it gas/rev it it would jump to 19-20 so do u think i have a vac leak? what are u sapose to have aat idle? :damnit: :damnit:

 

[CManT1914]

Stock cam I thought you were supposed to have a steady 19 or so. There's a number of things that can cause vacuum leaks, like bad gaskets (lower plenum to block, upper to lower intake, throttle body to intake), any vacuum line (like EGR, smog etc.).

 

[Tayohs 95Gt]

its stock cam.. so no rev or anything it should sit at a steady 19??

 

[CManT1914]

Yea I think stock cam is supposed to put out 19 or maybe 20 hg (or however it's measured) of vacuum. You can take a can of carb cleaner, and spray it over your gasket areas, and if the idle raises, then there's your vacuum leak. It will suck in the carb cleaner and burn it, hence the raise in the rpms. Also check your vacuum lines running off your tree (not all are for the engine, the real small one is for the a/c, but at least two run to the engine). Also check those lines running to your EGR, smog etc. My harness fell on the header and burned through all of those.

 

[Tayohs 95Gt]

I no longer have an EGR, I have an EGR plate. I capped the line to it. My smog pump is not hooked up either. I start the car and spray carb cleaner around it and if it raises the RPM's, then it is a leak? Is there a diagram of all the vacuum lines on a Mustang that I can locate or find anywhere?

 

[HISSIN50]

Where are you measuring the vac from? There are different vac sources/types.

Good luck.

 

[CManT1914]

I no longer have an EGR, I have an EGR plate. I capped the line to it. My smog pump is not hooked up either. I start the car and spray carb cleaner around it and if it raises the RPM's, then it is a leak? Is there a diagram of all the vacuum lines on a Mustang that I can locate or find anywhere?

Well you did cap off the lines running to the smog pump too right? Or are the valves and all that still there? If you removed the smog pump assembly, you'll need to cap off those vacuum lines running to the valves on the hoses coming off the back of the pump.

I don't think the carb cleaner will work with the smog pump lines, I doused my whole engine compartment with the stuff, and never got a raised idle, but my smog lines were sure as hell melted through. Anyway, those lines go to a box of some sort in ther fender. I've never seen it, but I know it's in there. Might check to see if they came undone there.

Unfortunately the only vacuum diagram I have is for the a/c/heating system, not much use here.

Oh, and answer JT's question!!

 

[Tayohs 95Gt]

Where are you measuring the vac from? There are different vac sources/types.

Good luck.

i pulled it off the fpr i put a T ther and read it off that

 

[OutLawSE]

My stock cam idles at 900rpm with 16lbs vac,